Hydraulic cutting tool



Dec. 11, 1951 w. E. NORTHCUTT HYDRAULIC CUTTING TOOL 2 Sl-{EETS--SHEET l Filed NOV. lO, 1948 .IIIM

Dec- 11, 1951 w. E. NoRTHcUTT HYDRAULIC CUTTING TOOL 2 SHEETS- SHEET 2 Filed Nov. lO, 1948 IIYVENTOR. fA/UfZ/zczz Patented Dec. 11, 1951 2,578,582 ICE HYDRAULIC CUTTING TOOL Walter E. Northcutt, Chebanse, Ill., assignor to Manco Mfg. Co., Bradley, Ill., a corporation of Illinois Application November 10, 1948, Serial No. 59,363

, 3 Claims.

This invention relates to hydraulic cutting tools, and has to do more particularly with a cutting tool suitable for cutting wire ropes or cables and analogous articles.

Hydraulic cutting tools are known and are used tor various purposes. In general, the known tools are excessively heavy and large, are cumbersome and diicult to handle, are rather expensive and have to be held in a certain manner or position in use. My invention is directed to the provision of a hydraulic cutting tool of compact construction, which will operate satisfactorily in any position, is of comparatively light weight and may be produced at comparatively low cost. It is also an object f my invention to provide a cutting tool of the character stated which is free or" objectionable projections such as would interfere with use of the tool in restricted spaces. The cutting tool of my invention comprises a cylinder and a piston operating therein providing, with the cylinder, a reservoir chamber at one side of the piston, for the operating hydraulic fluid or liquid, and a pressure chamber at the other side of the piston to which the operating liquid is delivered under pressure from the reservoir chamber, for applying high pressure to the piston and thereby forcing the cutting blade of the tool in cutting direction. By having a portion of the cylinder serve as a reservoir chamber, the overall dimensions of the tool may be reduced, which is conducive to compactness of construction and reduction in size of the tool. I also provide means .whereby the piston, and with it the cutting member or blade, may quickly be returned to outer or retracted position, upon completion of the cutting operation, which is desirable as increasing the cutting capacity of the tool. During the cutting operation, pressure is applied to the cutting blade by the piston rod in contact therewith, thereby reducing likelihood of breakage of parts, such as is apt to occur where the pressure is transmitted from the piston rod to the blade through a connecting pin or like member. I also provide pressure release means whereby the pressure at the high pressure side of the piston may be relieved `when it reaches a predetermined high value, thus guarding against breakage or damage to the tool, such pressure relief means being carried by the piston Within the cylinder so as to be guarded effectively thereby while avoiding objectionable projections beyond the cylinder. Further objects and advantages of my invention will appear from the detail description.

In the drawings:

Figures 1A and 1B taken together are a trans- .verse axial sectional view of a hydraulic cutting tool embodying my invention, certain parts being shown in plan and the inner cylinder head and ,the parts carried thereby being shown in plan,

the cylinder being shown fragmentarily in plan A,and broken away:

Figure 2 is an outer end view, on an enlarged scale, of the inner cylinder head and the cutter head and associated parts carried thereby;

Figure 3 is a sectional view, on an enlarged scale, taken substantially on line 3 3 of Figure 1; and

t Figure 4 is a sectional view, on an enlarged scale, taken substantially on line 4 4 of Figure 1, certain parts being shown in elevation, showing a wire cable being cut.

I have shown my invention as embodied in a cutting tool comprising a cylinder 5 closed at its outer end by a head 6 conveniently formedvintegral with cylinder 5. The cylinder 5 preferably is provided with a liner 'I fitting tightly therein for the major portion of the length thereof, the inner surface of this liner being accurately machined and polished. The other or inner end of cylinder 5 is closed by a head 3 bolted thereto and seating tightly thereon, this head 8 having an extension 9 fitting into the inner end of liner 'l providing a fluid tight and pressure resistant seal therewith. This tight t of extension E in the liner l, in conjunction with the accurate seating of head 8 upon the end of cylinder 5, ei'- fectively guards against leakage of hydraulic iiuid at the inner end of the cylinder. Within the broader aspects of my invention, any suitable known means may be provided to guard against such leakage, though the means shown is sufficient if proper care is exercised in machining and tting of the parts.

A piston Iii is mounted within cylinder 5 for reciprocaton therein. This piston is spaced from the cylinder heads 6 and 8 so as to provide a reservoir chamber II at one side of the piston and a pressure chamber I2 at the other side thereof. The piston I0 is provided with pressure resistant sealing means I3 of a suitable known type extending circumferentially thereabout adjacent the pressure chamber side of the piston, effective for preventing leakage of hydraulic iiuid under high pressure in chamber I2 about the piston. It will be seen that the cylinder and the piston provide both a reservoir chamber and a pressure chamber, thereby avoiding necessity of providing a hydraulic fluid reservoir chamber exterior of the piston, which is coniducive to compactness of construction.

The piston I0 is mounted upon a piston rod I 5 slidable through and extending beyond the piston heads 6 and 8. A sectional ring I6 seats in a corresponding groove extending about rod I5 in a corresponding recess in the inner `face of piston I0, eiective for preventing inward movement of piston I0 relative to rod I5. A washer I1 is disposed about rod I5 and seats on the outer face of piston I0, this washer being conned between the piston and a snap ring I8 engaging in a corresponding circumferential groove in rod I5. It will be clear, from what has been said, that the piston rod I5 is vsecured to the piston I9 for movement therewith lengthwise of cylinder 5. The piston I is provided, adjacent its outer face, with an annular recess extending about rod I and receiving an oil seal I9 of suitable known type effective for preventing leakage of hydraulic fluid or oil about rod I5 under the high pressures to which such iluid is subjected in the pressure chamber I2. A second snap ring ZI is mounted in a circumferential groove in piston rod i5, outward thereof beyond ring I8 and serves yas a stop, in cooperation with cylinder head 5, for limiting outward travel of piston rod I5. The piston head 5 is provided with a thickened element or boss 22, through which the piston rod I5 is slidable, this boss being provided with annular recesses extending about rod I5 in which are mounted seals 23 and 24 of suitable known type effective for preventing leakage about the piston rod of the hydraulic liquid subjected to high pressure in the pressure chamber I2.

The piston I5 is drilled from its outer end to provide an outer bore 26 opening through the outer end thereof, an intermediate bore 2i of less diameter than bore 'l5 and opening into the inner end thereof, and an inner bore 2S of less diameter than bore 2l' and opening into the innei` end thereof, this inner bore 28 terminating a short distance inward beyond the piston Iii. The piston rod I5 is further provided with a diametrical bore 23 intersecting bore 2S adjacent the inner end thereof and establishing communication between bore 2B and the reservoir chamber II of the cylinder. The outer end of bore 28 is slightly flared to provide a seat for a ball check valve 30, which opens outward away from bore 28 and normally is held seated by a light cornpression spring SI disposed in bore 2l and confined between valve and a tubular retainer 32 disposed in bore 2 and secured in position by a screw 33 extending through a wall of rod I5 and threading through the outward extension of retainer 32. The piston rod I5 is further provided with radial port 35 opening into bore 2i a short distance outward beyond the piston I0. The port 35 is controlled by a ball check valve 35 of known type comprising a casing having a reduced neck 31 threaded into a recess in piston rod I5 concentric with port 35.V The valve 35 comprises a ball valve member 3B which opens radially outward of the piston rod I5 and normally is held closed by a compression spring 39. This type of check valve is well known and requires no further description. Suiiice it to state that the port 35 is controlled by a suitable check valve which closes inward toward the piston rod I5 and opens outward radially thereof, the ball or valve member normally being yieldingly held seated or closed.

The outer end portion of bore 2 has a slight outward are and is threaded for engagement by a correspondingly formed and threaded element 4I of a pump barrel 42 thus secured in piston I5 coaxially therewith. Pump barrel 42 extends through bore 26 in concentric spaced relation to the surrounding wall of` piston rod I5 and projects outward a considerable distance beyond the outer end thereof. The outer end portion of piston rod I5 is reduced slightly in diameter to provide an annular shoulder 43 thereon. An elongated sleeve 44 fits about the reduced outer end portion of piston rod I5 and seats at its inner end on shoulder 43. The outer end of sleeve i5 fits about a reduced neck 45 of the head 45, the neck 45 of which screws onto a head 41 suitably secured, conventionally by Welding, on the outer Aend of pump barrel 42. Head 4G seats against the outer end of sleeve 44 and, in cooperation with shoulder 43, restrains it against endwise movement relative to piston rod I5 and pump barrel 42.

An elongated rod-like pump plunger is mounted in pump barrel 42 for reciprocation therein. This plunger extends outward through head 45, there being suitable known sealing means 5I and 52, carried by head e5, disposed about plunger 55 effective for guarding against leakage of hydraulic fluid or liquid outward thereabout. At its outer end the plunger 5U is secured in the plug 53 which is suitably secured, conveniently by spot welding, in the outer end of the tubular guide member 54 extending inward about sleeve 44 in concentric spaced relation thereto. A collar 55 is secured in the inner end of guide member 54, conveniently by spot welding, and is slidable along the outer end portion of piston rod I5 and along the sleeve 44. The plug member 53 is suitably bored and tapped for reception of a screw stud 5l of a handle 55 secured, by means of stud 5i, to plug 53. As will be clear from what has been said, the handle 58 provides means for reciprocating the plug 53, and with it the pump plunger 50 and the guide member 54, the latter, in cooperation with collar 55 and sleeve 44, serving to guide the plunger 5@ and guarding against objectionable flexing or bending thereof, conducive to ease and accuracy in operation of the pump.

The pump plunger 55 is of but slight diameter relative to pist-on iii, will be clear `from Figure l. On the outstroke of plunger 55', hydraulic liquid, preferably a light oil of suitable type and 1having a low freezing point, with which the cylinder chambers and communicating passages are filled, is withdrawn from the reservoir chamber II through the passage comprising the bores 23 and 2, into the pump barrel During such outstroke or suction stroke of the pump plunger 5G, the ball check valve 35 opens in opposition to the compression spring 3 I, which may be of cornparatively light weight, as will be understood. During the in or compression stroke of pump plunger 50, the oil withdrawn from the reservoir I I, is forced into the pressure chamber I2. During that stroke of the pump plunger the ball valve 38 of check valve 35 opens in opposition to the compression spring 35, which also is of comparatively light weight, and upon completion of the compression stroke of the pump plunger the ball valve 35 is seated and heid seated by the pressure in the pressure chamber I2, as will be und rstood. The total pressure exerted on the outer face o the piston i5 incident to the in stroke of pump plunger 55 is much greater than the total pressure applied to the pump plunger, as will be understood. It is desirable, in order to avoid. damage to the tool, that means be provided whereby excessively high pressure, such as cause damage, be guarded against. 'lio that end, I provide a pressure relief valve 5Fl, of suitable known type, mounted in the piston :53. rllhis valve comprises a housing 5I, which has a press fit in piston I3, this housing having a passage G2 opening into the pressure chamber i2. rlhe passage S2 is controlled by ball valve 53 yieldingly urged closed by a compression spring 55 mounted in a bore 55 of housing 5I, of greater diameter than the pag.- sage 52. A tubular spring retainer or collar is secured in the inner end of housing 5I. The piston I0 is urged toward the outer end of cylinder 5 by a compression spring 66 disposed about chamber 15.

piston rod I5 and confined between the extension 9 of head 8 and the piston I 0. It will be clear that as the piston I Il is forced inward by the pressure applied thereto at its outer face, the spring 68 is placed under increasing compression and presents increasing resistance to inward travel of piston I8. The spring 68 is of adequate strength to assure that the piston I9 will be returned to its outermost position, with the snap ring 2| in contact with head 6, when communication is established between pressure chamber I2 and reservoir I I for bypassing the hydraulic liquid about the piston I9, as will be explained more fully later. The maximum strength of spring 68 is slight compared to the total pressure applied to the outer face of piston I9 for forcing it inward and does not present any objectionable resistance to such inward movement of the piston. In the event the pressure within the pressure chamber I2 attains an objectionably high value, such as might result in injury to the tool, the pressure release valve 69 opens. That permits escape of the hydraulic liquid from the pressure chamber I2 to the reservoir chamber II, thereby effectively preventing any further increase in total pressure applied to the outer face of piston I0, even though operation of the pump being continued. Mounting the pressure relief valve I6 with the piston I8 assures that that valve is effectively enclosed and guarded and also eliminates objectionable projections beyond the cylinder 5, such as would result from positioning the pressure relief valve exteriorly of the cylinder.

The wall of cylinder 5 is thickened at one side thereof, at i9, this thickened portion of the cylinder wall extending from the boss 1| formed integral with the thickened portion or boss 22 of head 6. The thickened wall portion 19 of cylinder 5 is drilled to provide a duct 12 which opens through a port 'I3 in cylinder liner 1 into the reservoir chamber II. Duct 'I2 opens, at its outer end, into a duct 19 which opens, at its outer end, into a space in the inner end of boss 1I, between the inner end of bore 'I6 thereof and a flanged closure plug 11 threaded into boss 1|. The plug 11 is bored and tapped from its inner end for reception of the threaded enlargementl 18 of a valve stem 89 extending through plug 1'I and through a stuffing box 19 at the outer end of plug 11. A flanged handle or knob 8| is fixed on the outer end of stem 19. The valve stem 19 is provided, at its inner end, with a stud 82 disposed for contact with a ball valve 83 seating in a recess 84 extending inward from space or The ball valve 83 normally closes the outer end of a short duct 86 opening into the pressure chamber I2 at the outer end thereof. In the use of the tool, ball valve 83 is held seated by stud 82 and, in the operation of the pump, pressure is applied to the piston I0 as above described. Upon completion of the operation performed by the tool, it is desirable that the piston I0 be returned quickly to its outer position so as to condition the tool, without delay, for performing a succeeding operation. That is accomplished by turning the valve stem 19 outward a sufficient distance to permit opening of the ball valve 83. That valve is then opened by the pressure within the chamber I2, due to the outward pressure exerted by compression spring 68 on the piston I9. The piston I9 is quickly moved to its outermost position by spring 68, and the hydraulic liquid displaced from chamber I2 by this outward movement of piston I9 is by-passed about the'piston, through the-passage provided by the intersecting ducts and the associated spaces and ports, above described, and enters the reservoir chamber I I through the port 13. The valve stem 19 is then turned in so that the stud 82 holds the ball valve 83 tightly seated, and the tool is then conditioned for a further operation.

The inner cylinder head 8 carries a work receiving or cutter head 88 integrally connected to head 8 by a neck 89. The head 88 is of approximately U-shape in plan, comprising the two arms 99 and 89a defining between them a substantially U-shaped recess. The head 88, including neck 89 thereof, is suitably bored for reception of the inner end portion of piston rod I 5, slidable through head 8. The bore 92 (Figure 2) of head 88 and neck 89 is of greater diameter than bore 93 through head 8, which snugly receives the piston rod I5, providing clearance about rod I5 inward beyond cylinder head 8. Head 8-8 is further provided, at each side of bore 92, with a lengthwise groove 99 opening into bore 92, these grooves 94 being disposed in the plane of cutter head 88. At the outer end portion of head 88 and neck 89 thereof, the grooves 94 are of increased depth, at 99a, to provide clearance or relief for a cutting blade slidable in the grooves 99.

The grooves 94 slidably receive the side portions of a cutting blade 96 of hard steel. This blade is substantially lrectangular in plan and in transverse section, and is of considerable thickness, the side portions thereof being shaped conformably to and slidably mounted in the grooves 98. The inner end portion of blade 96 ts into a slot 91 in the outer end of piston rod I5, extending diametrically thereof. A pin 98 is secured in blade 98, conveniently by being a press t therethrough, adjacent the inner end thereof. This pin 98 extends through openings 99 in the fingers |89 at the sides of slot 91. The openings 69 are of somewhat greater extent lengthwise of piston rod I5 than the pin 98, providing in effect a pin and slot connection between blade 96 and piston rod I5. The pin 98 is so disposed that in the movement of piston rod I5 outward through head 8 the piston rod at the outer end of slot 91 contacts the inner end of blade 96, for transmitting directly thereto the pressure exerted by the piston rod and the associated piston. The fiat inner end of blade 96 seats against the corresponding flat area of the piston rod I5 during outward movement thereof, providing a substantial area of pressure contact therebetween, and ngers 99 of piston rod I5 assist in restraining blade 96 against twisting; as will be clear from what has been said and from Figure 4c. That reduces likelihood of breakage, such as might occur if the pressure from the piston rod were transmitted to the cutting blade through the pin99 or analogous member. When the piston rod is moved inward, after completion of a cutting operation, the fingers |99 thereof pick up the pin 98 and thereby move the blade 96 inward into retracted position with the piston rod I5, as will be understood.

The inner end portion of arm 99 of cutter head 88 is slotted for reception of one end portion of a yoke |92 pivoted therein by a pin |93. The yoke |92, when in itsnormal closed position, bridges the space between the arms 99 and 99a. The other arm 99o'. of cutter head 88 is slotted for reception of a latch member pivoted.

therein on'the pin |96. The latch member |65 is urged in latching direction, as viewed in Figure l, by compression spring v|91 confined between 4thtun'bpiece: |98- of -member`I95 and neck 89,

this spring seating at its ends in suitable recesses bored in the neck and in the thumb piece |08. At its inner end the latch member |05 is provided with a bill which engages over a cooperating extension |2 of yoke |02, for retaining the latter in its closed position. Movement of the latch member |05 in latching direction is limited by a nger H5 thereof disposed to contact the inner end of element H5 of cutter head 8B.

The yoke |92 is provided with a recess lit of approximately semi-circular shape into the sides of which open two grooves |29 corresponding to the grooves @il of cutter head 8S. The grooves 20 are continued through yoke |02 to the inner face thereof and the yoke |02 is slotted from recess lli; to its inner end face, for reception of the cutting blade 95. When yoke |92 secured in its normal closed position, the grooves thereof are aligned with the grooves @il of cutter head for reception of the side portions or" the blade S5. The latter, blade 95, is suitably formed and ground from one face thereof to provide a slightly concaved or beveled area l2! and, at the inner end of the blade, an approximately senil-circular recess defined by a cutting edge |22. The blade 90 is s0 disposed, relative to the yoke |52, that the unground or fiat face of blade S9 is presented to the fiat surface |2fl of yoke lei overlying slot therein (Figure ll) contiguous to the grooves |29. The upper wall of yoke ici, defining the recess i5, is beveled downward and inward at |25, to provide a cutting edge E26 dening the recess H3, in major portion.

In using the tool for cutting a wire cable c (Figure 4), with the piston i@ in its inner retracted position, with the blade 95 correspondingly retracted, the yoke |02 is released and swung to open position and is then closed, and secured closed, with the work piece, such as the cable c, disposed inthe recess i I8. With the ball valve held tightly seated in the manner previously described, the pump is operated thereby forcing the piston and with it the p-iston rod i5, outward oi cylinder 5 under high pressure. As the piston rod l5 is` forced outward it forces the cutting blade 96 outward toward the yoke 02, and the cable c is cut by the cutting edge 22 of blade 96 in cooperation with the cutting edge B2b oi the yoke |02.

The pressure of the piston rod I5 is applied thereby directly to the inner end of the blade 95 in direct contact therewith, during the outward travel of piston rod |5, thereby relieving pin 93 of stresses incident to the movement of blade 99 in cutting or outward direction, as above explained. Upon completion of the cutting operation, the valve stem 9'! is turned outward an appropriate distance and the compression spring |58 then returns the piston l0, and with it the piston rod i5 and blade 96, to retracted or inner position. The stem 19 is then turned inward so as to hold the ball valve 83 tightly seated and the tool is then conditioned for a second cutting operation. That permits of comparatively quick operation of the tool with a corresponding increase in the number of cutting operations possible in a given time period, breakage or damage of the tool due to excessive pressure during the cutting operation being guarded against by provision of the pressure relief valve EE, in the manner previously described.

It will be understood that changes in detail may be resorted toA without departing from the eld and scope of my invention, and I intend to include all such variations, as fall within the scope of the appended claims, in this application in which the preferred form only of my invention has been disclosed.

I claim:

l. In a hydraulic cutting tool, a cylinder having a closure head at each end, one of said heads having an extension providing a cutter head, a piston operating in said cylinder, a piston rod movable with said piston slidable through said one head, a cutting blade slidable in said cutter head guided thereby, said blade having an outer end and a fiat inner end of substantial area, and

, lost motion pin and slot operating connections between said rod and blade whereby said rod in its outward travel contacts the inner end of said blade for applying pressure thereto and in its inward travel picks up said blade and returns the latter to its inner position, said rod having a i'iat surface of substantial area disposed for pressure contact with the inner end of said blade in said outward travel of said rod.

2. In a hydraulic tool, a cylinder having al closure head at each end, one of said heads having an extension providing a work receiving head, a piston operating in said cylinder, a piston rod movable with said piston slidable through said one head, a pressure applying member slidable in said work receiving head guided thereby, said member having a nat inner end of substantial area, and a pin and slot connection between said rod and the inner end portion o said member providing lost motion therebetween whereby said rod in its outward travel contacts the inner end of said member for applying pressure thereto and its inward travel picks up said member and returns the latter to its inner position, said rod having a flat surface of substantial area disposed for pressure contact with the inner end of said member in said outward travel of said rod.

3. In a hydraulic tool, a cylinder having a closure head at each end, a pressure applying member having an inner portion of rectangular cross section and a flat inner end of substantial area, a piston operating in said cylinder, a piston rod movable with said piston slidable through said one head having in its outer end a transverse rectangular slot providing spaced lingers snugly receiving between them the inner end of member, said rod having at the inner end of said slot a fia-t surface of substantial area dhposed for pressure contact with the inner end of said member, said fingers having aligned slots therein, and a pin secured through said member extending into the slots of fingers, the latter slots providing for contact or" said rod in its outward travel with the inner end said member and for picking up of said pin by the fingers of said rod in its inward travel.

WALTER E. NORTHCUTT.

REFERENCES CKTEB The following references are of record in the Ene of this patent:

UNITED STATES PATENTS Number Name Date 706,481 Wilson Aug. 5, 1902 1,624,151 Shevlin Apr. 2, 1927 1,662,922 Helmer Mar. 20, 1928 2,053,720 Huck Sept. 8, 1936 2,257,245 Rudolph Sept. 30, 1941 2,385,419 Matulich Sept. 25, 1945 

